In daytime, intense solar
heating causes rocks to expands. At night, the temperature falls so rocks
cool and contrast. Repeated expansion and contraction produce stress along
joints. Joints are then widened and deepened and finally break down the
rocks block by block.

Block
disintegration is common over well-jointed granite in Hong Kong. It is
especially significant over area with little vegetation cover because of
the large diurnal range of temperature.